Rectangular Kapton Heater — Polyimide Etched-Foil

A rectangular Kapton heater is what you reach for when a flat component or surface needs heat but has no room for a conventional heater — a battery cell, a wafer chuck, an optical mount or an instrument wall. The element is an etched metal foil sealed between two layers of polyimide film, so it lies flat against the part and brings it to temperature in seconds without adding bulk or holding heat after the power is cut.

Because the foil carries the heat and the film stores almost none, the heater follows a controller closely, and the polyimide outgasses very little — the two properties that put these heaters into vacuum chambers, clean tools and sealed assemblies.

Purpose — Heating where there is no room for a heater

Many components cannot take a conventional heater: there is no clearance for one, the extra thermal mass would slow the response the process depends on, or a bulkier heater would outgas into a vacuum or contaminate a clean step. Left unheated, a cold battery will not deliver current, condensation forms on optics and sensors, and viscous or temperature-sensitive parts sit out of spec.

A polyimide film heater removes that compromise. At 0.2 to 0.3 mm it disappears into the assembly, adds almost no mass, and puts the heat exactly where it is needed while staying clean enough for the most sensitive environments.

How it works in practice

The self-adhesive version is pressed onto a clean, flat or single-curve surface; the plain version is held against the surface by a clamp or fixture. The heater runs from a 12 V DC supply sized to the load, controlled by a thermostat or controller reading a sensor. The thermostat measures the temperature of the foil itself, not of the part being heated, so a heater that is well bonded to its surface runs safely while a poorly bonded one can overheat at the same setting.

Key features

• Etched-foil element in polyimide (Kapton) film, 0.2 to 0.3 mm — fits and responds where a thicker heater cannot
• Very low outgassing, CVCM 0.02% to ASTM E595 — works in vacuum and clean processes without filming nearby surfaces
• Silicone-free construction — safe on processes that silicone would spoil, such as paint preparation, optics and electronics
• 12 V DC, SELV — no shock hazard and no electrical approval needed on the element, suitable in wet, laboratory and medical settings
• Two power levels per size — gentle holding and anti-condensation, or faster warm-up against a heat path
• Self-adhesive or plain backing — bonded mounting to about 180 °C, or clamped mounting to 200 °C

Certification & Approvals

• Outgassing tested to ASTM E595: CVCM 0.02%, TML 1.54%, WVR 0.64%
• 12 V DC — SELV (safety extra-low voltage); no electrical certification required on the element

The standard range is not offered with UL or VDE recognition; a UL-recognised polyimide construction is a custom build.

Technical Specifications

• Material: polyimide (Kapton) film, encapsulated etched-foil element
• Voltage: 12 V DC
• Operating temperature: −40 to +200 °C (film)
• Mounting temperature: self-adhesive to about 180 °C, plain to 200 °C
• Thickness: 0.2 mm plain, 0.3 mm self-adhesive
• Maximum surface loading: 0.8 W/cm² in open air
• Leads: 0.3 m, 22 AWG
• Outgassing (ASTM E595): CVCM 0.02%, TML 1.54%, WVR 0.64%
• Backing options: self-adhesive (low-outgassing 3M PSA) or plain, non-adhesive
• Sizes and power: 25 × 50 mm (1.25 or 7.5 W); 25 × 75 mm (2 or 11 W); 25 × 100 mm (4 or 15 W); 50 × 50 mm (2.5 or 15 W); 50 × 75 mm (3.75 or 22.5 W); 50 × 100 mm (5 or 30 W); 75 × 100 mm (7.5 or 45 W)

Applications

• EV and equipment battery warming for cold-temperature performance
• Semiconductor and wafer handling, and other vacuum-process tooling
• Optics and display assemblies needing even, low-mass heat
• Laboratory instruments and medical devices
• Anti-condensation and defrost on enclosures, cameras and sensors
• Telecom and aerospace assemblies where space and weight are tight

Operational Requirements

• Requires a 12 V DC supply sized to the load (a 45 W part draws 3.75 A) and a thermostat or controller with a sensor — the heater does not self-regulate
• Flexible but not elastic — apply to flat or single-curve surfaces only; never force onto compound or spherical shapes or the foil circuit will crack
• Self-adhesive backing is rated to about 180 °C; above that, clamp the plain version between plates with a thin (about 0.5 mm) silicone buffer
• Not intended for continuous immersion — moisture eventually enters at the laminated edges
• Bond the heater well to its surface; high surface loading without a heat path will overheat the element

Selection guidance

Choose the lower power for gentle, even warming such as anti-condensation or holding a temperature, and the higher power for faster warm-up where the heat is carried away into a substrate. Pick self-adhesive for mounting up to about 180 °C, or plain when the surface runs hotter and the heater is clamped in place. If you need higher watt density with the heat path designed in, temperatures toward 260 °C, mains voltage at 115 or 230 V, a bespoke shape with cut-outs, or an integrated sensor, request a custom heater. To compare with the round version and the wider range, see our Kapton heater category.